> Date: Thu, 07 Dec 2000 08:18:10 EST> From: NATURNUT_at_aol.com> Subject: Re: NANFA-- Milfoil Update/Wintering Pond Plants>> In michigan we have something called "Eurasian water milfoil", which is an exotic> milfoil, a very serious threat, and a danger to our wetlands. Does anyone know how to> tell the eurasian species from the other milfoils? I use milfoil in my tanks, and need to> make sure I'm not helping to spread the plant. Also, do most milfoils(once they reach> the surface)develop into a plant that grows above the surface? Thanks --Dan>

Once you've seen it the Eurasian species is not hard to identify. The
leaves are very feathery looking and often are encrusted with carbonates
when the plant grows in hard water.

This site has a photographic comparison of Eurasian Milfoil to the
native Northern Milfoil - M. exalbescens.
You probably have the Farwell's Milfoil M. farwellii & the Whorled - M.
verticillatum and maybe a few other species. Making a correction to my
article in American Currents the Red-stemmed Foxtail is the variable
milfoil M. heterophyllum which also comes in a green stemmed variant
which also confused me about the true green foxtail which is the Cutleaf
or Eastern Milfoil - M. pinnatum. We collected heterophyllum in
Wisconsin so it might be in your area too either as a native or
introduced. This species has both a good and bad rep - In some states it
is considered 'endangered' but in North Carolina where it is a common
native it considered noxious and in Massachusettes where it was
introduced it and Cabomba (also introduced) may be almost as bad as the
Eurasian species.
If you are growing any live plants in an aquarium and make sure that you
destroy any surplus material and make sure anyone you trade or give
cuttings is informed of the importance of not allowing these plants to
escape cultivation - that should prevent infestations. The Eurasian
species I've dabbled with in the past but ironically it did not seem to
like my pond and died out. It may not care for acidic waters which many
of the natives seem to thrive in.
In Cranberry Lake in Somersette Co PA the Eurasian species has recently
made a debut where it grows alongside the native Whorled Milfoil. So far
it seems restrained. It is possible that part of the problem with all
potentially invasive aquatic plants - natives as well as exotics is
overfertilization of waters by fertilizer runnoff from lawns and
agriculture. Cranberry Lake is in a remote rural setting and seems to
have a healthy balance of vegetation.

A promising biocontrol is the Milfoil Weevil which normally eats the
native Northern Milfoil but when raised in the lab on a diet of the
exotic one will perfer it over the native.

Jeff

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